Pop-up antihelo mine

ABSTRACT

A pop-up mine, anchored to the bottom and remaining under the surface of a body of water for destroying ASW and sonar dunking helicopters. The mine case includes an outer skin comprising fragment projectiles bonded to an explosive sheet. Deployed by a submarine, an anchor separates and sinks to the bottom, paying out cable to leave the mine close to the surface. A hydrophone, discriminating for detecting helicopters, activates a cable cutter and a rocket motor. The mine case pops to the surface, is lifted by the rocket to a predetermined altitude, and explodes to disperse the metal fragments, thus disabling the helicopter.

0 United States Patent 11 1 1111 3 838 62 Shimberg Oct. 1, 1974 1 POP-UPANTIHELO MINE 3,293,676 12/1966 Link 102/18 x v 3,513,750 5/1970 Penza89/1.809 [75] Invent Lee slver SPrmg 3,675,577 7/1972 Sternberg 102 67[73] Assignee: The United States of America as represented the Secretaryof the Primary Examiner-Ben amin Bol'chelt Nay w i to AssistantExaminer-C. T. Jordan Art A r F RSS"JACk orne, en, 22 Filed: Nov. 15,1972 g g c'asma 6 [21] Appl. No.: 306,971

[57] ABSTRACT A pop-up mine, anchored to the bottom and remain- [52] US.Cl 102/10, 89/1.809, 191221136 ing under the Surface Ofa body of waterfor destroying 51 1m. (:1. F42b 22/18, F42b 22/26 g fim g j tl l Q if[58] Field 61 Search 102/7, 10, 13, 16, 14; b e er S P comprsmg ragme esonded to an exploswe sheet. Deployed by a subma- 89/1.809, 1.81, 114/20,21

rme, an anchor separates and Sll'ikS to the bottom, t cable to leave themine close to the sur- [56] References Cited paymg f.Ahdh,d tfdtthl-UNITED STATES PATENTS 1 16. 36325;": c$ilir ndL rififel iofol. 1,588,9326 1926 Blair 114 21 A i' fii'ii gag ga s to the surface, is lifted bythe rocket to a predetermined altitude, and explodes to 1c ieson3,010,416 [1961 114/23 ggspterrse the metal fragments, thus dlsablmg thehel1 3,045,596 7/1962 244/311 p 3,093,033 6/1963 Draim et al 89/1.809 8Claims, 4 Drawing Figures PATENIEUBCI H 3.838.642

sum HP 3 FIG.2

l? I Q4 68 I72 i 70 40 Q I k POW 66 ,./22 SUP POP-UP ANTIHELO MINEBACKGROUND OF THE INVENTION This invention relates generally tounderwater weapons systems such as mines and torpedoes and moreparticularly to a pop-up mine that detects and destroys ASW helicoptershovering over the water having the intent to detect and destroy asubmarine At present there is no known offensive weapon that may beeffectively used by a submarine to attack an Anti-Submarine Warfarehelicopter or airplane. The submarine may only defensively hide byrunning away or diving deep to avoid detection and subsequent attack.The use of the deck gun of the older submarines required that thesubmarine expose itself by surfacing to fire on the aircraft.

The instant invention provides an offensive weapon for a submarine touse effectively against ASW aircraft that is triggered by the attackingaircraft.

SUMMARY OF THE INVENTION Accordingly, an object of the present inventionis to provide an effective sea-to-air offensive weapon.

Another object of the instant invention is to provide a submarine withan effective offensive weapon against ASW aircraft.

A further object of the instant invention is to provide a mine that isconcealed under the sea surface which is released 'and lifted to analtitude to disable an aircraft.

A still further object of the present invention is to provide a minethat is activated by and will disable the attacking aircraft.

Briefly, these and other objects of the present invention are attainedby a pop-up mine concealed below the waters surface that detects anddestroys ASW helicopters hovering over the water with the intent tolocate and destroy a submarine. The mine is deployed by a submarine, andsubsequently releases a separable anchor which sinks to the bottomleaving the mine case concealed just below the surface of the water. Adiscriminating hydrophone, on the mine case, picks up the low frequencynoise created by the downwash of a helicopter rotor when it is searchingor dunking to listen for submarines. Upon hearing a helicopter, thehydrophone activates an anchor cable cutter and a rocket motor, causingthe mine case to pop to the surface and be lifted to a predeterminedaltitude. The outer skin of the mine, composed of metal fragments bondedto an explosive sheet, is caused to explode, releasing flack projectileswhich disable the helicopter.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of theinvention and the many attendant advantages thereof will be readilyappreciated as the same becomes better understood by DESCRIPTION OF THEPREFERRED EMBODIMENT Referring now to the drawings, wherein like refer-5 ence numerals designate corresponding parts throughout the severalviews. there is shown generally in FIG. 1 a pop-up mine in an air-seaenviroment 12. A submarine 14 is shown as having just planted the minesystem by expelling it out a garbage ejector or torpedo tube port 16 asshown in position A.

After planting as shown in position B the pop-up mine 10 separates,leaving a mine case 18 floating concealed under the surface, and aseparable anchor 20 sinks to the bottom paying out a mooring line 22. Inpo- 5. sition C the mine is activated by cutting the mooring line 22 andenergizing a rocket motor to pop to the surface (position D) and ascendto a height to disable a hovering and dunking ASW helicopter 24(position E).

20 Referring now to FIG. 2, the mine case 18, anchor 20, and mooringline 22 are shown in detail. The mine case 18 comprises a pair ofhemispheres 26 of thin spun aluminum or the like overlaid with aplurality of sheets 28 of Starrflak. Starrflak" is a Naval OrdnanceLaboratory invention comprising a grid of one-fourth inch square metalfragments bonded to an explosive sheet. The Starrflak may be overlaidwith cheesecloth laminated on with an epoxy resin or the like. Thehemispheres are secured together along flanges 30 using suitablefasteners and sealed with a rubber gasket 32. A cable 34 from a batteryand firing assembly 36 (to be discussed hereinafter) inside the case,exits through a stuffing gland 38 and is electrically connected to adetonator 40 on each hemisphere 26 and attached to the Starrflak" by anadhesive or the like. Further, the cable 34 is electrically connected toa rocket motor and mooring line cutter initiator squib assembly 42.

Alongside the mooring line cutter and inside the case is a rocket motor44 affixed to a mounting plate 46 sealed to the bottom of the case. Themounting plate contains a plurality of ports 48 through which the motorpropulsive exhaust exits. The ports are sealingly closed by a port plate50 secured by shear screws 52.

On top of the mine case 18 are flush-mounted hydrostats 54 which act asarming switches and a hydrophone 56 for activating the mine.l-Iydrophone 56 is electrically connected via a cable 58 to preamp 60located at the bottom of the mine case, along with other electronicscircuitry.

Referring now to FIG. 3 the electronic circuit contained in the batteryand firing assembly 36 is shown in detail. The hydrophone 56 iselectrically connected to an electronic filter 62 which passes only thedesired low frequency band produced by the downwash of a helicopterrotor. The filters output is fed via cable 58 to the signal preamplifier60 which produces a usable output. This output is fed to an electronicswitch 64 capable of initiating the rocket motor and mooring line cutterinitiator squib 42. The signal preamp 60 derives its power from abattery 66 electrically connected thereto.

current to the hydrophone preamp'60, the electronic switch 64 and thenceto the initiator 42, and a firing circuit comprising a charging resistor68, and a firing cathe mooring depth of mine case 18.

'In operation, the pop-up antihelo mine '10 is planted (View A) by thevery submarine 14 that the ASW hovering helicpoter 24 is attempting tolocate, by deploy ing the mine out the garbage ejector 16. Afterejection, the anchor 20 separates from the mine case 18, paying outmooring line 22, and sinks to the bottom (View B) keeping the casesubmerged. When the anchor sinks below a predetermined depth, themooring line spool 78 pawls and the anchor continues to the bottom.Pawling occurs a distance from the bottom equal to the desired casemooring depth, and is controlled by hydrostats 82 or the like.

Electrical arming of the mine occurs after ejection from the submarineand during the anchoring phase,

tance. Referring to FIG. 3 arming occurs by water pressure actuating thehydrostatic switches 54 causing power from battery 66 to be applied tothe hydrophone preamplifier 60, the arming circuit resistor 68 andcapacitor 70 charging it and the electronic switch 64.

The pop-up mine system now waits in position (FIG. 1, View'B) for a'ASWhovering, dunking helicopter. When a helicopter 24 nears the location,the hydro phone 56 picks up the low-frequency sound and pressure wavescreated by the rotor downwash. The electrical output of the hydrophone56 is fed through filter 62 which passes only low frequency signals, andcancels high frequency sound emitted from passing shipping, ambientnoise, sonar and marine life. The low frequency signal is fed via thecable 58 to the hydrophone preamplified 60. If the output is ofsufficient magnitude, the electronic switch 64, such as a relay orsilicon ,controlled rectifier, will activate applying a current to therocket motor and mooring line cutter squib 42.

When the squib fires, the mooring line 22 is severed by squib 42 and therocket motor 44 ignited, blowing out the jet port plates 50, allowingthe mine case 18 to pop to the surface of the water and be lifted by therocket into the air to an altitude of feet to 150 feet depending on therocket used. At the apogee, the inertia or velocity discriminator apogeeswitch 72 closes, dumping the charge in the firing capacitor 70 into thedetonators 40, detonating the Starrflak and spraying the area with metalfragments to disable the ASW helicopter.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. lt is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A pop-up, anti-helo mine system adapted to be moored below the waterssurface and to be propelled into the air upon detection of an air'targetcomprising:

allowing the submarine to cruise to a safe standoff dis a mine caseadapted to be moored below the water's surface;

an explosive attached to said mine case;

an anchor assembly releasably connected to said minecase;

a mooring line connecting said anchor assembly to said mine case;

means for paying out said mooring line from said anchor assembly;

an acoustic detection device provided in said mine case to detect.target signals above the waters surface;

propulsion means for propelling said mine case out of the water; and

control means responsive to said acoustic detection device to releasesaid anchor assembly and to activate said propulsion means.

2, The pop-up, anti-helo mine system'of claim 1, V

wherein said propulsion means comprises a solid rocket motor forpropelling said mine to a predetermined altitude above the waterssurface; 3. The pop-up, anti-helo mine system of claim 2, wherein saidacoustic detection device comprises:

a hydrophone capable of receiving sounds in water and converting them toelectrical impulses;

an electrical filter connected to said hydrophone for passing only lowfrequencies produced by a helicopter; and i a preamplifier foramplifying the impulses to a magnitude capable of activating the mine.

. 4. The pop-up, anti-helo mine system of claim 3 wherein said controlmeans comprisesa rocket motor and cable cutter initiator squibelectrically connected to said acoustic detection device for releasingsaid mooring line and igniting said rocket motor when said hydrophonedetects a helicopter.

5. The popup, anti-helo mine system of claim 4 wherein said explosivecomprises:

a metal sheet segmented to produce a plurality of metal fragments; and

an explosive sheet bonded to said metal sheet,

whereby the resulting laminant forms the outer shell of said mine case.

6. The pop-up, anti-helo mine system of claim 4 further comprising:

a firing circuit including a chargeable capacitor and resistor;

at least one electro-responsive detonator in contact with saidexplosive; and

an apogee switch for coupling said firing circuit to saidelectro-responsive detonator to initiate said detonator and consequentlysaid explosive.

7. The pop-up, anti-helo mine system of claim 6 further comprising aplurality of hydrostatically operated arming switches for connecting asource of electrical power to said acoustic detection device, saidinitiator squib, and said firing circuit after deploying and anchoring.

8. The pop-up, anti-helo mine system of claim 7 wherein said means forpaying out mooring line comprises:

a spool for winding said anchor line; and

a pawling mechanism coacting with said spool for releasing and stoppingsaid spool.

1. A pop-up, anti-helo mine system adapted to be moored below thewater''s surface and to be propelled into the air upon detection of anair target comprising: a mine case adapted to be moored below thewater''s surface; an explosive attached to said mine case; an anchorassembly releasably connected to said mine case; a mooring lineconnecting said anchor assembly to said mine case; means for paying outsaid mooring line from said anchor assembly; an acoustic detectiondevice provided in said mine case to detect target signals above thewater''s surface; propulsion means for propelling said mine case out ofthe water; and control means responsive to said acoustic detectiondevice to release said anchor assembly and to activate said propulsionmeans.
 2. The pop-up, anti-helo mine system of claim 1, wherein saidpropulsion means comprises a solid Rocket motor for propelling said mineto a predetermined altitude above the water''s surface.
 3. The pop-up,anti-helo mine system of claim 2, wherein said acoustic detection devicecomprises: a hydrophone capable of receiving sounds in water andconverting them to electrical impulses; an electrical filter connectedto said hydrophone for passing only low frequencies produced by ahelicopter; and a preamplifier for amplifying the impulses to amagnitude capable of activating the mine.
 4. The pop-up, anti-helo minesystem of claim 3 wherein said control means comprises a rocket motorand cable cutter initiator squib electrically connected to said acousticdetection device for releasing said mooring line and igniting saidrocket motor when said hydrophone detects a helicopter.
 5. The pop-up,anti-helo mine system of claim 4 wherein said explosive comprises: ametal sheet segmented to produce a plurality of metal fragments; and anexplosive sheet bonded to said metal sheet, whereby the resultinglaminant forms the outer shell of said mine case.
 6. The pop-up,anti-helo mine system of claim 4 further comprising: a firing circuitincluding a chargeable capacitor and resistor; at least oneelectro-responsive detonator in contact with said explosive; and anapogee switch for coupling said firing circuit to saidelectro-responsive detonator to initiate said detonator and consequentlysaid explosive.
 7. The pop-up, anti-helo mine system of claim 6 furthercomprising a plurality of hydrostatically operated arming switches forconnecting a source of electrical power to said acoustic detectiondevice, said initiator squib, and said firing circuit after deployingand anchoring.
 8. The pop-up, anti-helo mine system of claim 7 whereinsaid means for paying out mooring line comprises: a spool for windingsaid anchor line; and a pawling mechanism coacting with said spool forreleasing and stopping said spool.